Semiconductor device and manufacturing method thereof

ABSTRACT

A method of manufacturing a semiconductor device is provided. The method includes providing a substrate; forming a well region on the substrate; forming at least one first gate structure on the well region, wherein the first gate structure includes a gate insulating layer and a first gate electrode formed on the gate insulating layer, wherein the first gate electrode is formed having a first enclosed pattern on a surface of the well region; wherein an area inside the first enclosed pattern is defined as a first region, and an area outside the first enclosed pattern is defined as a second region; performing ion implantation on the first region such that the first region has a first conductivity type, and performing ion implantation on the second region such that the second region has a second conductivity type, wherein the first conductivity type and the second conductivity type are different.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of U.S. application Ser. No. 14/661,944filed on Mar. 18, 2015, which application claims priority to ChinesePatent Application No. 201410169272.4 filed on Apr. 25, 2014, thedisclosures of which are incorporated herein by their reference.

BACKGROUND

Technical Field

The present disclosure relates to a semiconductor device and amanufacturing method thereof.

Description of the Related Art

Electrostatic discharge (ESD) is a key factor affecting the reliabilityof integrated circuits. ESD is the rapid neutralization of electricalcharges. The high electrostatic voltage in ESD can damage and causefailures in an integrated circuit. To protect the integrated circuitfrom damage due to ESD, an ESD protection circuit may be fabricated intothe integrated circuit.

A gated diode has faster speeds, lower resistance, and higher faultcurrent compared to a conventional STI (Shallow Trench Isolation) diode.Accordingly, the gated diode is increasingly being used in the ESDprotection circuit.

FIG. 1 illustrates a gated diode of an ESD protection circuit in theprior art. Referring to FIG. 1, the gated diode is formed having a longstriped pattern. The gated diode includes an active area comprising a P⁺conductive region 1, a gate electrode 2, and an N⁺ conductive region 3.The length of the active area is given by W. The widths of the P⁺conductive region 1, gate electrode 2, and N⁺ conductive region 3 aregiven by Lp, Lg, and Ln, respectively.

FIG. 2 is a cross-sectional view of the gated diode of FIG. 1. As shownin FIG. 2, conduction current in the gated diode flows from the P⁺conductive region 1 to the N⁺ conductive region 3 (in the directionindicated by the arrows 4).

To obtain adequate ESD protection, the size of the gated diode needs tobe increased. However, increasing the size of the gated diode may resultin increased parasitic capacitance which could impact deviceperformance. In particular, the performance degradation is moresignificant for high speed RF (Radio Frequency) integrated circuits.

SUMMARY

The present disclosure addresses at least the above issues relating tothe conventional gated diode in an ESD protection circuit.

According to one embodiment of the inventive concept, a method ofmanufacturing a semiconductor device is provided. The method includesproviding a substrate; forming a well region on the substrate; formingat least one first gate structure on the well region, wherein the firstgate structure includes a gate insulating layer and a first gateelectrode formed on the gate insulating layer, wherein the first gateelectrode is formed having a first enclosed pattern on a surface of thewell region; wherein an area inside the first enclosed pattern isdefined as a first region, and an area outside the first enclosedpattern is defined as a second region; performing ion implantation onthe first region such that the first region has a first conductivitytype, and performing ion implantation on the second region such that thesecond region has a second conductivity type, wherein the firstconductivity type and the second conductivity type are different.

In some embodiments, the method may further include forming a firstisolation region in the first region, wherein the first isolation regionis spaced apart from a boundary of the first region.

In some embodiments of the method, a ratio of a perimeter length of thefirst isolation region to a perimeter length of the first region mayrange from about 0.25 to about 0.75.

In some embodiments, the method may further include forming a secondgate structure on the well region, wherein the second gate structure isspaced apart from the first gate structure, wherein the second gatestructure includes the gate insulating layer and a second gate electrodeformed on the gate insulating layer, wherein the second gate electrodeis formed having a second enclosed pattern on the surface of the wellregion, and the second enclosed pattern is surrounded by the firstregion, wherein an area inside the second enclosed pattern is defined asa third region; and performing ion implantation on the third region suchthat the third region has the second conductivity type.

In some embodiments, the method may further include forming a secondisolation region in the third region, wherein the second isolationregion is spaced apart from a boundary of the third region.

In some embodiments of the method, a ratio of a perimeter length of thesecond isolation region to a perimeter length of the third region mayrange from about 0.25 to about 0.75.

In some embodiments of the method, the well region may be a P-type wellregion, the first region having the first conductivity type may be an N⁺conductive region, and the second region having the second conductivitytype may be a P⁺ conductive region.

In some embodiments of the method, the first gate electrode may be apolysilicon gate, and a distance between adjacent first gate electrodesmay range from about 0.1 μm to about 2 μm.

In some embodiments of the method, an inner contour and an outer contourof the first enclosed pattern, and an outer contour of the firstisolation region, may have at least one of the following shapes:quadrilateral, pentagonal, hexagonal, octagonal, circular, andelliptical.

In some embodiments of the method, an outer contour and an inner contourof the first enclosed pattern, and an outer contour and an inner contourof the second enclosed pattern, may have the same respective shapes.

According to another embodiment of the inventive concept, asemiconductor device is provided. The semiconductor device includes asubstrate; a well region disposed on the substrate; at least one firstgate structure disposed on the well region, wherein the first gatestructure includes a gate insulating layer and a first gate electrodeformed on the gate insulating layer, wherein the first gate electrode isformed having a first enclosed pattern on a surface of the well region,wherein an area inside the first enclosed pattern is defined as a firstregion, and an area outside the first enclosed pattern is defined as asecond region, wherein the first region has a first conductivity type,and the second region has a second conductivity type, and wherein thefirst conductivity type and the second conductivity type are different.

In some embodiments, the semiconductor device may further include afirst isolation region disposed in the first region, wherein the firstisolation region is spaced apart from a boundary of the first region.

In some embodiments of the semiconductor device, a ratio of a perimeterlength of the first isolation region to a perimeter length of the firstregion may range from about 0.25 to about 0.75.

In some embodiments, the semiconductor device may further include: asecond gate structure disposed on the well region, wherein the secondgate structure is spaced apart from the first gate structure, whereinthe second gate structure includes the gate insulating layer and asecond gate electrode formed on the gate insulating layer, wherein thesecond gate electrode is formed having a second enclosed pattern on thesurface of the well region, and the second enclosed pattern issurrounded by the first region, wherein an area inside the secondenclosed pattern is defined as a third region, and the third region hasthe second conductivity type.

In some embodiments, the semiconductor device may further include asecond isolation region disposed in the third region, wherein the secondisolation region is spaced apart from a boundary of the third region.

In some embodiments of the semiconductor device, a ratio of a perimeterlength of the second isolation region to a perimeter length of the thirdregion may range from about 0.25 to about 0.75.

In some embodiments of the semiconductor device, the well region may bea P-type well region, the first region having the first conductivitytype may be an N⁺ conductive region, and the second region having thesecond conductivity type may be a P⁺ conductive region.

In some embodiments of the semiconductor device, the first gateelectrode may be a polysilicon gate, and a distance between adjacentfirst gate electrodes may range from about 0.1 μm to about 2 μm.

In some embodiments of the semiconductor device, an inner contour and anouter contour of the first enclosed pattern, and an outer contour of thefirst isolation region, may have at least one of the following shapes:quadrilateral, pentagonal, hexagonal, octagonal, circular, andelliptical. In some embodiments of the semiconductor device, an outercontour and an inner contour of the first enclosed pattern, and an outercontour and an inner contour of the second enclosed pattern, may havethe same respective shapes.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutea part of the specification, illustrate different embodiments of theinventive concept and, together with the detailed description, serve todescribe more clearly the inventive concept.

It is noted that in the accompanying drawings, for convenience ofdescription, the dimensions of the components shown may not be drawn toscale. Also, same or similar reference numbers between differentdrawings represent the same or similar components.

FIG. 1 depicts a plan view of a conventional gated diode having a longstriped pattern.

FIG. 2 depicts a schematic cross-sectional view of the conventionalgated diode of FIG. 1.

FIG. 3 is a flowchart illustrating a method of manufacturing asemiconductor device according to an embodiment of the inventiveconcept.

FIG. 4, FIG. 5, FIG. 6, FIG. 7, FIG. 8, FIG. 9, FIG. 10, and FIG. 11depict different views of the semiconductor device at different stagesof manufacture according to a first embodiment of the inventive concept.

FIG. 12 and FIG. 13 respectively depict a plan view and a schematiccross-sectional view of a semiconductor device according to a secondembodiment of the inventive concept.

FIG. 14 and FIG. 15 respectively depict a plan view and a schematiccross-sectional view of a semiconductor device according to a thirdembodiment of the inventive concept.

FIG. 16 and FIG. 17 respectively depict a plan view and a schematiccross-sectional view of a semiconductor device according to a fourthembodiment of the inventive concept.

FIG. 18 depicts a plan view of a semiconductor device according to afifth embodiment of the inventive concept.

FIG. 19 depicts a plan view of a semiconductor device according to asixth embodiment of the inventive concept.

FIG. 20 depicts a plan view of a semiconductor device according to aseventh embodiment of the inventive concept.

FIG. 21 depicts a plan view of a semiconductor device according to aneighth embodiment of the inventive concept.

FIG. 22 depicts a plan view of a semiconductor device according to aninth embodiment of the inventive concept.

DETAILED DESCRIPTION

Various embodiments of the inventive concept are next described indetail with reference to the accompanying drawings. It is noted that thefollowing description of the different embodiments is merelyillustrative in nature, and is not intended to limit the inventiveconcept, its application, or use. The relative arrangement of thecomponents and steps, and the numerical expressions and the numericalvalues set forth in these embodiments do not limit the scope of theinventive concept unless otherwise specifically stated. In addition,techniques, methods, and devices as known by those skilled in the art,although omitted in some instances, are intended to be part of thespecification where appropriate. It should be noted that for convenienceof description, the sizes of the elements in the drawings may not bedrawn to scale.

In the drawings, the sizes and/or relative sizes of layers and regionsmay be exaggerated for clarity. Like reference numerals denote the sameelements throughout.

It will be understood that, although the terms “first,” “second,”“third,” etc. may be used herein to describe various elements, theelements should not be limited by those terms. Instead, those terms aremerely used to distinguish one element from another. Thus, a “first”element discussed below could be termed a “second “element withoutdeparting from the teachings of the present inventive concept. As usedherein, the term “and/or” includes any and all combinations of one ormore of the associated listed items.

It should be understood that the inventive concept is not limited to theembodiments described herein. Rather, the inventive concept may bemodified in different ways to realize different embodiments.

Referring to FIG. 1, the current conduction capability of theconventional gated diode is dependent upon the outer contour length(i.e. conductive length) of the N⁺ conductive region 3. The size of aparasitic capacitance 5 is determined by the size of the bottom area ofthe N⁺ conductive region 3. In an ESD protection circuit, the gateddiode should preferably have high current conduction capability and lowparasitic capacitance.

In the present disclosure, a parameter k is defined, whereby k is aratio of the conductive length to the bottom area of the N⁺ conductiveregion (i.e., k=conductive length/bottom area). The ESD protectioncapability of the gated diode improves as the parameter k increases.

Referring to the conventional gated diode in FIGS. 1 and 2, itsconductive length is given by 2W, and the bottom area of the N⁺conductive region 3 is given by W×Ln. Accordingly, the parameter k(0) ofthe conventional gated diode is given by:

${k(0)} = {\frac{2 \times W}{W \times {Ln}} = \frac{2}{Ln}}$

The inventive concept discloses an exemplary gated diode havingincreased current conduction capability and lower parasitic capacitancecompared to the conventional gated diode. Specifically, the parameter kof the exemplary gated diode is higher than the parameter k(0) of theconventional gated diode. Accordingly, the exemplary gated diode hasimproved ESD protection capability compared to the conventional gateddiode.

FIG. 3 is a flowchart illustrating a method of manufacturing asemiconductor device according to an embodiment of the inventiveconcept. The method includes the following steps.

Referring to Step 301, a substrate is provided, and a well region isformed in the substrate. In one embodiment, the well region may be aP-type well region. In one embodiment, Step 301 may further includeforming separation grooves on the substrate, and forming the well region(between the separation grooves) on the substrate.

Referring to Step 302, at least one first gate structure is formed onthe well region. The first gate structure may include a gate insulatinglayer and a first gate electrode formed on the gate insulating layer.The first gate electrode on the well region is formed having a firstenclosed pattern. The area inside the first enclosed pattern is definedas a first region, and the area outside the first enclosed pattern isdefined as a second region.

In one embodiment, the first gate electrode may be formed ofpolysilicon. In one embodiment, a plurality of first gate structures maybe formed, and a distance between adjacent first gate electrodes mayrange from about 0.1 μm to about 2 μm.

In one embodiment, a plurality of first gate structures may be formed,whereby the gate structures may be spaced apart from each at differentintervals, and the gate structures may be formed having different shapesand sizes.

In one embodiment, a plurality of first gate structures may be formed,whereby the gate structures may have different sizes and are formed in anested structure.

In one embodiment, the method may further include forming a firstisolation region in the first region, whereby the first isolation regionis spaced apart from a boundary of the first region. Preferably, thefirst isolation region may be formed at the same time as the separationgrooves in Step 301.

In one embodiment, a ratio of the perimeter length of the firstisolation region to the perimeter length of the first region may rangefrom about 0.25 to about 0.75.

In one embodiment, an inner contour and an outer contour of the firstenclosed pattern, and an outer contour of the first isolation region,may have at least one of the following shapes: quadrilateral,pentagonal, hexagonal, octagonal, circular, and elliptical.

In one embodiment, at least two gate structures may be formed in anested structure. The nested structure may be formed as follows. Forexample, a second gate structure may be formed on the well region suchthat the second gate structure is spaced apart from the first gatestructure. The second gate structure includes the gate insulating layerand a second gate electrode formed on the gate insulating layer. Thesecond gate electrode on the well region is formed having a secondenclosed pattern. The second enclosed pattern is surrounded by the firstenclosed pattern, such that the area inside the second enclosed patternis defined as a third region.

In one embodiment, the first and second gate structures may be formedsimultaneously.

In one embodiment, the second gate electrode may be formed ofpolysilicon.

In one embodiment, the method may further include forming a secondisolation region in the third region, whereby the second isolationregion is spaced apart from a boundary of the third region. Preferably,the second isolation region may be formed at the same time as theseparation grooves in Step 301.

In one embodiment, a ratio of the perimeter length of the secondisolation region to the perimeter length of the third region may rangefrom about 0.25 to about 0.75.

In one embodiment, the outer contour and the inner contour of the secondenclosed pattern may have the same shape as the outer contour and theinner contour of the first enclosed pattern.

Referring to Step 303, ion implantation is performed on the first regionto form a region having a first conductivity type. In one embodiment,the region having the first conductivity type may be an N⁺ region.

Referring to Step 304, ion implantation is performed on the secondregion to form a region having a second conductivity type, whereby thesecond conductivity type is different from the first conductivity type.

In one embodiment, if the second gate structure is formed in Step 302,the method may further include performing ion implantation on the thirdregion to form a region having the second conductivity type.

In one embodiment, the region having the second conductivity type may bea P⁺ conductive region.

In one embodiment, the inner contour of the first enclosed pattern maybe any closed pattern, whereby the ratio of the perimeter length of theinner contour to the area of the N⁺ conductive region satisfies thefollowing condition:

${k > \frac{2}{Ln}} = {k(0)}$

whereby Ln is a width of a conventional long striped pattern gateddiode.

In one embodiment in which the semiconductor device does not include theisolation region or the second gate structure, the following conditionis still satisfied:

${k > \frac{2}{Ln}} = {k(0)}$

Comparing the semiconductor device in the above embodiment to anequivalent conventional long striped pattern gated diode in which bothhave the same ESD protection capability, the semiconductor device haslower parasitic capacitance compared to the conventional gated diode.Accordingly, the exemplary semiconductor device can help to improve thecircuit performance of an RF integrated circuit.

In one embodiment, when the semiconductor device includes an isolationregion, the isolation region is formed within the N⁺ conductive region,thereby reducing the area of the N⁺ conductive region. Accordingly, theparameter k is increased in the above embodiment. Comparing theaforementioned semiconductor device (having increased k) to anequivalent conventional long striped pattern gated diode in which bothhave the same ESD protection capability, the aforementionedsemiconductor device has much lower parasitic capacitance compared tothe conventional gated diode. Accordingly, the aforementionedsemiconductor device can help to further improve the circuit performanceof the RF integrated circuit.

In one embodiment, when the semiconductor device includes a second gatestructure, the P⁺ conductive region and the second gate electrode areformed within the N⁺ conductive region, thereby further reducing thearea of the N⁺ conductive region. In addition, the current path from theP⁺ conductive region to the N⁺ conductive region is increased. Theaforementioned semiconductor device has improved ESD protectioncapability and lower parasitic capacitance compared to the conventionalgated diode. Accordingly, the aforementioned semiconductor device canhelp to further improve the circuit performance of the RF integratedcircuit.

Next, the method of FIG. 3 will be described with reference to FIGS.3-11, which depict different views of the semiconductor device atdifferent stages of manufacture according to a first embodiment of theinventive concept.

First Embodiment

The method of manufacturing the semiconductor device according to thefirst embodiment includes the following steps.

First, as shown in FIG. 4, a substrate 6 is provided. In one embodiment,the substrate 6 may be a silicon substrate. In one embodiment, thesubstrate 6 may include a base layer, an epitaxial layer, and an oxidelayer. Specifically, FIG. 4 is a schematic cross-sectional view of thesemiconductor device taken along a direction perpendicular to thesurface of the substrate 6.

Next, as shown in FIG. 5, an isolation trench 71 is formed in thesubstrate 6. In one embodiment, the isolation trench 71 is formed as ashallow isolation trench. In one embodiment, forming the isolationtrench 71 on the substrate 6 includes: etching the substrate 6 to formthe isolation trench 71; filling the isolation trench 71 using ahigh-density plasma chemical vapor deposition process; and performingchemical mechanical polishing (CMP) for planarization. Specifically,FIG. 5 is a schematic cross-sectional view of the semiconductor devicetaken along a direction perpendicular to the surface of the substrate 6after the isolation trench 71 has been filled/planarized.

Next, as shown in FIG. 6, ion implantation is performed on the substrate6 to form a well region 8. In a preferred embodiment, boron ionimplantation may be carried out at a power of about 100-200 keV, and ata dosage of about 10¹³ cm⁻², to form a P-well. Specifically, FIG. 6 is aschematic cross-sectional view of the semiconductor device taken along adirection perpendicular to the surface of the well region 8 after thewell region 8 has been formed.

Next, as shown in FIGS. 7 and 8, a first gate structure is formed on thewell region 8.

The first gate structure includes a gate insulating layer (not shown)and a first gate electrode 21 formed on the gate insulating layer. Thefirst gate electrode 21 is formed having a first enclosed pattern on thesurface of the well region 8. The area inside the first enclosed patternis defined as a first region 81, and the area outside the first enclosedpattern is defined as a second region 82. Specifically, FIG. 7 is aschematic cross-sectional view of the semiconductor device taken along adirection perpendicular to the surface of the well region 8 after thefirst gate structure has been formed. FIG. 8 is a plan view of an activeregion of the semiconductor device after the first gate structure hasbeen formed.

In a preferred embodiment, the first gate electrode 21 may be apolysilicon gate.

In one embodiment, forming the first gate structure on the well region 8may include forming the gate insulating layer on the well region 8, anddepositing polycrystalline silicon on the gate insulating layer to forma polysilicon gate (i.e. the first gate electrode 21).

In one embodiment, the first enclosed pattern may be formed as anannular ring.

In one embodiment, the outer contour and the inner contour of the firstenclosed pattern have a square shape. Accordingly, the outer contours ofthe first region 81 and the second region 82 are formed as symmetricsquares with respect to the center of the first enclosed pattern. Asshown in FIG. 8, the first region 81 is a square having a width Ln, thefirst enclosed pattern is an annular square ring having a width Lg, andthe second region 82 is an annular square ring having a width Lp.

Next, as shown in FIGS. 9 and 10, ion implantation is performed in thefirst region 81 to form a region 3 of a first conductivity type, ionimplantation is performed in the second region 82 to form a region 11 ofa second conductivity type, wherein the first conductivity type and thesecond conductivity type are different. In one embodiment, the region 3of the first conductivity type is an N⁺ conductive region and the region11 of the second conductivity type is a P⁺ conductive region. As shownin FIG. 10, the outer contour and the inner contour of the firstenclosed pattern have a square shape. Accordingly, the outer contours ofthe P⁺ conductive region and the N⁺ conductive region are formed assymmetric squares with respect to the center of the first enclosedpattern. Specifically, the N⁺ conductive region is a square having thewidth Ln, the first enclosed pattern is an annular square ring havingthe width Lg, and the P⁺ conductive region is an annular square ringhaving the width Lp. FIG. 9 is a schematic cross-sectional view of thesemiconductor device taken along a direction perpendicular to thesurface of the conductive regions (i.e. the N⁺ and P⁺ conductiveregions) after the conductive regions have been formed. FIG. 10 is aplan view of the active region of the semiconductor device after theconductive regions have been formed.

In one embodiment, forming the N⁺/P⁺ conductive regions may includeforming a spacer (e.g. a silicon nitride spacer) on the first gateelectrode 21, performing N⁺/P⁺ ion implantation, and performing asilicidation process on the N⁺/P⁺ conductive regions.

In one embodiment, Lp and Lg may range from about 0.1 μm to about 2 μm,and Ln may range from about 0.1 μm to about 10 μm.

Next, after the isolation layer has been deposited and processed, an ESDprotection circuit is fabricated into the semiconductor device. As shownin FIG. 11, the first gate electrode 21 and the P⁺ conductive region 11are connected to the input/output of the ESD protection circuit, and theN⁺ conductive region 3 is connected to the power supply (Vdd). FIG. 11illustrates the connectivity between the components of the semiconductordevice according to the first embodiment of the inventive concept. Asshown in FIGS. 10 and 11, according to the first embodiment of thesemiconductor device, conduction current flows from the P⁺ conductiveregion 11 (in a direction perpendicular to the four sides of the N⁺conductive region 3) into the N⁺ conductive region 3. Accordingly, theparameter k(1) of the first embodiment of the semiconductor device isgiven by the ratio of the perimeter length to the area of the(square-shaped) N⁺ conductive region 3:

${k(1)} = {\frac{4 \times {Ln}}{{Ln} \times {Ln}} = {{\frac{4}{Ln} > \frac{2}{Ln}} = {k(0)}}}$

The parameter k(1) of the first embodiment of the semiconductor deviceis greater than the parameter k(0) of the conventional long stripedpattern gated diode. Comparing the first embodiment of the semiconductordevice to an equivalent conventional long striped pattern gated diode inwhich both have the same ESD protection capability, the first embodimentof the semiconductor device has lower parasitic capacitance compared tothe conventional gated diode. Accordingly, the first embodiment of thesemiconductor device can help to improve the circuit performance of anRF integrated circuit.

Second Embodiment

FIGS. 12 and 13 respectively depict a plan view and a schematiccross-sectional view of a semiconductor device according to a secondembodiment of the inventive concept.

The second embodiment of the semiconductor device can be manufacturedusing some or all the steps previously described with reference to FIGS.3-11. The first and second embodiments of the semiconductor device aresimilar except for the following differences.

Referring to FIG. 12, an isolation region 72 may be formed in a firstregion, whereby the isolation region 72 is spaced apart from a boundaryof the first region. FIG. 12 is a plan view of the active region of thesecond embodiment of the semiconductor device after the conductiveregions have been formed. Similar to FIG. 10, the N⁺ conductive region 3in FIG. 12 is a square having the width Ln. In contrast to FIG. 10, theembodiment in FIG. 12 further includes the isolation region 72 formed asa square that is symmetric to the outer contour of the N⁺ conductiveregion 3. The width of the isolation region 72 is given by Ls (where Lsis less than Ln).

Referring to FIG. 12, conduction current flows from the P⁺ conductiveregion 11 (in a direction perpendicular to the four sides of the N⁺conductive region 3) into the N⁺ conductive region 3, and therefore thenumerator of the parameter k (conductive length) remains unchanged.However, the area of the N⁺ conductive region 3 is reduced by theisolation region 72. Accordingly, the parameter k(2) of the secondembodiment of the semiconductor device is given by:

${k(2)} = {\frac{4 \times {Ln}}{{{Ln} \times {Ln}} - {{Ls} \times {Ls}}} = {\frac{4}{{Ln} - \frac{{Ls}^{2}}{Ln}} > \frac{4}{Ln} > {k(1)}}}$

In the second embodiment of the semiconductor device, the area of the N⁺conductive region is decreased and as a result, parasitic capacitance isreduced. Accordingly, the ESD protection capability is improved whichhelps to further improve the circuit performance of an RF integratedcircuit.

In one embodiment, Lp and Lg may range from about 0.1 μm to about 2 μm,and Ln may range from about 0.1 μm to about 10 μm.

In one embodiment, the ratio of the perimeter lengths of the isolationregion and the first region is equal to the ratio of the widths of theisolation region and the first region (Ls/Ln). The ratio Ls/Ln may rangefrom about 0.25 to about 0.75.

In one embodiment, the isolation region 72 may be formed in the firstregion at the same time when forming the isolation trench 71 in thesubstrate (refer back to the first embodiment depicted in FIG. 5).

Since the other manufacturing process steps in the first and secondembodiments are similar, a detailed description of those similar processsteps shall be omitted. FIG. 13 illustrates the connectivity between thecomponents of the semiconductor device according to the secondembodiment of the inventive concept. Specifically, FIG. 13 illustratesthe circuit connections in the active region after the conductiveregions have been formed.

In the second embodiment of the semiconductor device, the shape of theisolation region 72 may be different from the shape of the N⁺ conductiveregion. The shape of the isolation region 72 may be pentagonal,hexagonal, octagonal, circular, oval, or any closed shape.

In the second embodiment of the semiconductor device, a plurality ofcell structures may be formed within the isolation region 72, so as toform a nested structure. Each cell structure includes the N⁺ conductiveregion, gate electrodes, and P⁺ conductive region (extending in anoutward direction). The conduction current can be further increasedusing the nested structure, thereby improving the current conductioncapability of the semiconductor device.

Third Embodiment

FIGS. 14 and 15 respectively depict a plan view and a schematiccross-sectional view of a semiconductor device according to a thirdembodiment of the inventive concept.

The third embodiment of the semiconductor device can be manufacturedusing some or all the steps previously described with reference to FIGS.3-11. The second and third embodiments of the semiconductor device aresimilar except for the following differences.

Referring to FIG. 14, a second gate structure may be formed on the wellregion, whereby the second gate structure is spaced apart from the firstgate structure. The second gate structure may include the gateinsulating layer and a second gate electrode 22 formed on the gateinsulating layer. The second gate electrode on the well region is formedhaving a second enclosed pattern, with the second enclosed pattern beingsurrounded by the first region. The area inside the second enclosedpattern is defined as a third region. Ion implantation is performed onthe third region to form a region of the second conductivity type. FIG.14 is a plan view of the active region of the third embodiment of thesemiconductor device after the conductive regions have been formed.

Similar to FIG. 10, the N⁺ conductive region 3 in FIG. 14 is a squarehaving the width Ln. In contrast to FIG. 10, the embodiment in FIG. 14further includes the square-shaped P⁺ conductive region 12 and thesecond gate electrode 22 formed symmetrically within the N⁺ conductiveregion 3. The centers of the P⁺ conductive region 12 and the second gateelectrode 22 coincide with the center of the outer contour of the N⁺conductive region 3. The outer contour of the second gate electrode 22is a square having a width Lg₂. A width of the third region is the sameas a width of the P⁺ conductive region 12 and is given by Lp₂, such thatLp₂<Lg₂<Ln.

In one embodiment, Lp and Lg may range from about 0.1 μm to about 2 μm.Ln, Lp₂, and Lg₂ may range from about 0.1 pm to about 10 μm.

In one embodiment, the second gate structure may be formed at the sametime as the first gate structure (refer back to the first embodimentdepicted in FIG. 7). As previously described, the first gate structureis formed on the substrate, and the second gate structure is formedspaced apart from the first gate structure on the well region.

In one embodiment, ion implantation is performed on the third region toform a region of a second conductivity type (i.e. the P⁺ conductiveregion 12 having a width Lp₂). The ion implantation on the third regionmay be performed at the same time as the ion implantation on the secondregion (refer back to first embodiment depicted in FIG. 9). Aspreviously described, ion implantation is performed on the second regionto a form a region having a second conductivity type (i.e. the P⁺conductive region 11). In other words, the P⁺ conductive regions in thesecond and third regions may be simultaneously formed.

Since the other manufacturing process steps in the first and thirdembodiments are similar, a detailed description of those similar processsteps shall be omitted. FIG. 15 illustrates the connectivity between thecomponents of the semiconductor device according to the third embodimentof the inventive concept. Specifically, FIG. 15 illustrates the circuitconnections in the active region after the conductive regions have beenformed.

As shown in FIGS. 14 and 15, according to the third embodiment of thesemiconductor device, conduction current flows inward from the P⁺conductive region 11 towards the square-shaped N⁺ conductive region 3,and outward from the P⁺ conductive region 12 towards the square-shapedN⁺ conductive region 3. The numerator of the parameter k (conductivelength) is greater in the third embodiment of FIG. 14 than in the firstembodiment of FIG. 10. In addition, the area of the N⁺ conductive region3 is reduced by the P⁺ conductive region 12 (having the width Lp₂) sincethe P⁺ conductive region 12 is formed within the N⁺ conductive region 3.Accordingly, the parameter k(3) of the third embodiment of thesemiconductor device is given by:

${k(3)} = {\frac{{4 \times {Ln}} + {4 \times {Lp}_{2}}}{{{Ln} \times {Ln}} - {{Lg}_{2} \times {Lg}_{2}}} = {\frac{4\left( {1 + \frac{{Lp}_{2}}{Ln}} \right)}{{Ln} - \frac{{Lg}_{2}^{2}}{Ln}} > \frac{4}{Ln} > {k(1)}}}$

Referring to FIG. 14, the semiconductor device according to the thirdembodiment further includes the second gate electrode 22 and the P⁺conductive regions 11 and 12. Accordingly, the conduction current isincreased, thereby increasing the numerator of the parameter k.

At the same time, the area of the N⁺ conductive region 3 is reduced,thereby decreasing the denominator of the parameter k. Accordingly, theparasitic capacitance is reduced and the ESD protection capability isimproved. Accordingly, the third embodiment of the semiconductor devicecan help to further improve the circuit performance of an RF integratedcircuit.

Fourth Embodiment

FIGS. 16 and 17 respectively depict a plan view and a schematiccross-sectional view of a semiconductor device according to a fourthembodiment of the inventive concept.

The fourth embodiment of the semiconductor device can be manufacturedusing some or all the steps previously described with reference to FIGS.3-11. The fourth and third embodiments of the semiconductor device aresimilar except for the following differences.

Referring to FIG. 16, an isolation region 73 is formed in the thirdregion, whereby the isolation region 73 is spaced apart from a boundaryof the third region. FIG. 16 is a plan view of the active region of thefourth embodiment of the semiconductor device after the conductiveregions have been formed.

Similar to FIG. 14, the P⁺ conductive region 12 in FIG. 16 is a squarehaving the width Lp₂. In contrast to FIG. 14, the embodiment in FIG. 16further includes the square-shaped isolation region 73 formed within theP⁺ conductive region 12, and that is symmetric with the outer contour ofthe P⁺ conductive region 12. The centers of the isolation region 73 andthe P⁺ conductive region 12 coincide with each other. A width of thesquare-shaped isolation region 73 is given by Ls₂, wherebyLs₂<Lp₂<Lg₂<Ln.

In one embodiment, Lp and Lg may range from about 0.1 μm to about 2 μm.Ln, Ls₂, Lp₂, and Lg₂ may range from about 0.1 μm to about 10 μm.

Referring to FIG. 16, the flow of the conduction current and the area ofthe N⁺ conductive region in the fourth embodiment of the semiconductordevice are the same as the third embodiment. Accordingly, the parameterk(4) of the fourth embodiment of the semiconductor device is the same asthe parameter k(3) in the third embodiment:

${k(4)} = {{k(3)} = {\frac{{4 \times {Ln}} + {4 \times {Lp}_{2}}}{{{Ln} \times {Ln}} - {{Lg}_{2} \times {Lg}_{2}}} = {\frac{4\left( {1 + \frac{{Lp}_{2}}{Ln}} \right)}{{Ln} - \frac{{Lg}_{2}^{2}}{Ln}} > \frac{4}{Ln} > {k(1)}}}}$

The fourth embodiment is similar to the third embodiment in that theparasitic capacitance is reduced and the ESD protection capability isimproved. Accordingly, the fourth embodiment of the semiconductor devicecan help to further improve the circuit performance of an RF integratedcircuit.

In one embodiment, the ratio of the perimeter lengths of the isolationregion and the third region is equal to the ratio of the widths of theisolation region and the third region (Ls₂/Lp₂). The ratio Ls₂/Lp₂ mayrange from about 0.25 to about 0.75.

In one embodiment, the isolation region 73 may be formed in the thirdregion at the same time when forming the isolation trench 71 in thesubstrate (refer back to the first embodiment depicted in FIG. 5).

Since the other manufacturing process steps in the third and fourthembodiments are similar, a detailed description of those similar processsteps shall be omitted. FIG. 17 illustrates the connectivity between thecomponents of the semiconductor device according to the fourthembodiment of the inventive concept. Specifically, FIG. 17 illustratesthe circuit connections in the active region after the conductiveregions have been formed.

Fifth Embodiment

FIG. 18 depicts a plan view of a semiconductor device according to afifth embodiment of the inventive concept. Specifically, FIG. 18 is aplan view of the active region of the semiconductor device after theconductive regions have been formed.

The fifth embodiment of the semiconductor device can be manufacturedusing some or all the steps previously described with reference to FIGS.3-11. The fifth and first embodiments of the semiconductor device aresimilar except for the following differences.

Referring to FIG. 18, the first gate electrode 2 is formed having afirst enclosed pattern, and the inner and outer contours of the firstenclosed pattern are circular. The outer contour of the N⁺ conductiveregion 3 is also circular.

According to the fifth embodiment of the semiconductor device, theparameter k(5) of the semiconductor device is given by the ratio of thecircumference to the area of the circular N⁺ conductive region 3:

${k(5)} = {\frac{\pi \times {Ln}}{\pi \times \left( {{Ln}/2} \right)^{2}} = {{\frac{4}{Ln} > \frac{2}{Ln}} = {k(0)}}}$

The parameter k(5) of the semiconductor device according to the fifthembodiment is greater than the parameter k(0) of the conventional longstriped pattern gated diode. Comparing the fifth embodiment of thesemiconductor device to an equivalent conventional long striped patterngated diode in which both have the same ESD protection capability, thefifth embodiment of the semiconductor device has lower parasiticcapacitance compared to the conventional gated diode. Accordingly, thefifth embodiment of the semiconductor device can help to improve thecircuit performance of an RF integrated circuit.

In one embodiment, Lp and Lg may range from about 0.1 μm to about 2 μm.Ln may range from about 0.1 μm to about 10 μm.

Sixth Embodiment

FIG. 19 depicts a plan view of a semiconductor device according to asixth embodiment of the inventive concept. Specifically, FIG. 19 is aplan view of the active region of the semiconductor device after theconductive regions have been formed. The sixth embodiment of thesemiconductor device can be manufactured using some or all the stepspreviously described with reference to FIGS. 3-11. The sixth and firstembodiments of the semiconductor device are similar except for thefollowing differences.

Referring to FIG. 19, the first gate electrode 2 is formed having afirst enclosed pattern, and the inner contour of the first gateelectrode 2 and the outer contour of the N⁺ conductive region 3 arecircular. However, the outer contour of the first gate electrode 2 issquare.

According to the sixth embodiment of the semiconductor device, theparameter k(6) of the semiconductor device is given by the ratio of thecircumference to the area of the circular N⁺ conductive region 3:

${k(6)} = {{k(5)} = {\frac{\pi \times {Ln}}{\pi \times \left( {{Ln}/2} \right)^{2}} = {{\frac{4}{Ln} > \frac{2}{Ln}} = {k(0)}}}}$

The parameter k(6) of the semiconductor device according to the sixthembodiment is greater than the parameter k(0) of the conventional longstriped pattern gated diode. Comparing the sixth embodiment of thesemiconductor device to an equivalent conventional long striped patterngated diode in which both have the same ESD protection capability, thesixth embodiment of the semiconductor device has lower parasiticcapacitance compared to the conventional gated diode. Accordingly, thesixth embodiment of the semiconductor device can help to improve thecircuit performance of an RF integrated circuit.

Seventh Embodiment

FIG. 20 depicts a plan view of a semiconductor device according to aseventh embodiment of the inventive concept. Specifically, FIG. 20 is aplan view of the active region of the semiconductor device after theconductive regions have been formed.

The seventh embodiment of the semiconductor device can be manufacturedusing some or all the steps previously described with reference to FIGS.3-11. The seventh and first embodiments of the semiconductor device aresimilar except for the following differences.

Referring to FIG. 20, the first gate electrode 2 is formed having afirst enclosed pattern. The inner and outer contours of the first gateelectrode 2 and the outer contour of the N⁺ conductive region 3 haveregular hexagonal shapes.

According to the seventh embodiment of the semiconductor device, theparameter k(7) of the semiconductor device is given by the ratio of theperimeter length to the area of the hexagonal N⁺ conductive region 3:

${k(7)} = {\frac{3 \star {Ln}}{{\frac{3}{8}\sqrt{3}} \star {Ln} \star {Ln}} = {{\frac{4.62}{Ln} > \frac{2}{Ln}} = {k(0)}}}$

The parameter k(7) of the semiconductor device according to the seventhembodiment is greater than the parameter k(0) of the conventional longstriped pattern gated diode. Comparing the seventh embodiment of thesemiconductor device to an equivalent conventional long striped patterngated diode in which both have the same ESD protection capability, theseventh embodiment of the semiconductor device has lower parasiticcapacitance compared to the conventional gated diode. Accordingly, theseventh embodiment of the semiconductor device can help to improve thecircuit performance of an RF integrated circuit.

It should be noted that the fifth to seventh embodiments of thesemiconductor device differ from the first embodiment of thesemiconductor device in that the shapes of the first gate electrode aredifferent.

In the fifth to seventh embodiments, the isolation region is formed inthe first region, whereby the isolation region is spaced apart from aboundary of the first region. Since the step of forming the isolationregion in the first region is similar to the corresponding steppreviously described with reference to the second embodiment, a detaileddescription of the step shall not be repeated.

In the fifth to seventh embodiments, a second gate structure is formedon the well region, whereby the second gate structure is spaced apartfrom the first gate structure. The second gate structure includes a gateinsulating layer and a second gate electrode formed on the gateinsulating layer. The second gate electrode on the well region is formedhaving a second enclosed pattern, with the second enclosed pattern beingsurrounded by the first region. The area inside the second enclosedpattern is defined as a third region. Ion implantation is performed onthe third region so as to form a region of the second conductivity type.An isolation region is formed in the third region, whereby the isolationregion is spaced apart from a boundary of the third region. Since thesteps of forming the second gate structure, the third region, and theisolation region in the third region are similar to the correspondingsteps previously described with reference to the third and fourthembodiments, a detailed description of the step shall not be repeated.

Eighth Embodiment

FIG. 21 depicts a plan view of a semiconductor device according to aneighth embodiment of the inventive concept. Specifically, FIG. 21 is aplan view of the active region of the semiconductor device after theconductive regions have been formed.

Referring to FIG. 21, a plurality of cell structures are formed in aregular distribution on a substrate. Each of the cell structuresincludes the N⁺ conductive region, gate electrode, and P⁺ conductiveregion (extending in an outward direction) previously described withreference to the first embodiment in FIG. 10. The distribution of theplurality of cell structures (i.e. nested structure) causes the area ofthe N⁺ region to increase, which increases the conduction current,thereby improving the current conduction capability of the semiconductordevice.

In one embodiment, Lp and Lg may range from about 0.1 μm to about 2 μm,and Ln may range from about 0.1 μm to about 10 μm.

In one embodiment, a distance between adjacent cell structures may begiven by Lp, as shown in FIG. 21.

In one embodiment, a distance between adjacent first gate electrodes mayrange from about 0.1 μm to about 2 μm.

Also, it should be noted that the cell structures may include any of thestructures previously described in the second to seventh embodiments ofthe semiconductor device (for example, those depicted in FIGS. 12, 14,16, and 18-20).

In one embodiment, the shape of the outermost P⁺ conductive region inthe cell structure should not be substantially different from the shapeof the isolation groove. In particular, the shape of the outermost P⁺conductive region in the cell structure may be adapted to the shape ofthe isolation groove, as described below in the ninth embodiment of thesemiconductor device.

Ninth Embodiment

FIG. 22 depicts a plan view of a semiconductor device according to aneighth embodiment of the inventive concept. Specifically, FIG. 22 is aplan view of the active region of the semiconductor device after theconductive regions have been formed.

The ninth embodiment in FIG. 22 is similar to the eighth embodiment inFIG. 21 except for the following difference.

Referring to FIG. 22, a plurality of cell structures are formed in aregular distribution on a substrate, and have the same cell structure asthe fifth embodiment of FIG. 18. Although the outer contour of the P⁺conductive region in each cell structure has a circular shape (e.g. asthat shown in FIG. 18), the outer contours are combined together in thedistribution array to form a square shape, such that the shape of theoutermost P+conductive region in the cell structure is adapted to theshape of the isolation groove.

In one embodiment, a distance between adjacent cell structures may begiven by Lp, as shown in FIG. 22.

In one embodiment, a distance between adjacent first gate electrodes mayrange from about 0.1 μm to about 2 μm.

According to another embodiment of the inventive concept, asemiconductor device is provided. The semiconductor device includes asubstrate, a well region disposed on the substrate, and at least onefirst gate structure disposed on the well region. The first gatestructure includes a gate insulating layer and a first gate electrodeformed on the gate insulating layer. The first gate electrode is formedhaving a first enclosed pattern on the surface of the well region. Thearea inside the first enclosed pattern is defined as a first region, andthe area outside the first enclosed pattern is defined as a secondregion. The first region includes a region of a first conductivity type,and the second region includes a region of a second conductivity type,whereby the first conductivity type and the second conductivity type aredifferent.

In one embodiment, the semiconductor device may further include anisolation region disposed in the first region, whereby the isolationregion is spaced apart from a boundary of the first region.

In one embodiment, the semiconductor device may further include a secondgate structure formed on the well region, whereby the second gatestructure is spaced apart from the first gate structure. The second gatestructure includes a gate insulating layer and a second gate electrodeformed on the gate insulating layer. The second gate electrode on thewell region is formed having a second enclosed pattern, with the secondenclosed pattern being surrounded by the first region. The area insidethe second enclosed pattern is defined as a third region. The thirdregion includes a region of the second conductivity type.

In one embodiment, the semiconductor device may further include anisolation region disposed in the third region, whereby the isolationregion is spaced apart from a boundary of the third region.

In one embodiment, the ratio of the perimeters of the isolation regionand the third region may range from about 0.25 to about 0.75.

In one embodiment, the well region is a P-type well region; the regionof the first conductivity type is an N⁺ region, and the region of thesecond conductivity type is a P⁺ region.

In one embodiment, the first gate electrode is a polysilicon gate, and adistance between adjacent first gate electrodes may range from about 0.1μm to about 2 μm.

In one embodiment, an inner contour and an outer contour of the firstenclosed pattern, and an outer contour of the first isolation region,may have at least one of the following shapes: quadrilateral,pentagonal, hexagonal, octagonal, circular, and elliptical.

In one embodiment, the outer and inner contours of the first enclosedpattern and the outer and inner contours of the second enclosed patternhave the same shapes.

Embodiments of a semiconductor device and methods of manufacturing thesemiconductor device have been described in the foregoing description.To avoid obscuring the inventive concept, details that are well-known inthe art may have been omitted. Nevertheless, those skilled in the artwould be able to understand the implementation of the inventive conceptand its technical details in view of the present disclosure.

The different embodiments of the inventive concept have been describedwith reference to the accompanying drawings. However, the differentembodiments are merely illustrative and are not intended to limit thescope of the inventive concept. Furthermore, those skilled in the artwould appreciate that various modifications can be made to the differentembodiments without departing from the scope of the inventive concept.

What is claimed is:
 1. A semiconductor device, comprising: a substrate;a well region disposed on the substrate; at least one first gatestructure disposed on the well region, wherein the first gate structureincludes a gate insulating layer and a first gate electrode formed onthe gate insulating layer, wherein the first gate electrode is formedhaving a first enclosed pattern on a surface of the well region, whereinan area inside the first enclosed pattern is defined as a first region,and an area outside the first enclosed pattern is defined as a secondregion, wherein the first region has a first conductivity type, and thesecond region has a second conductivity type, and wherein the firstconductivity type and the second conductivity type are different.
 2. Thesemiconductor device according to claim 1, further comprising: a firstisolation region disposed in the first region, wherein the firstisolation region is spaced apart from a boundary of the first region. 3.The semiconductor device according to claim 2, wherein a ratio of aperimeter length of the first isolation region to a perimeter length ofthe first region ranges from about 0.25 to about 0.75.
 4. Thesemiconductor device according to claim 1, further comprising: a secondgate structure disposed on the well region, wherein the second gatestructure is spaced apart from the first gate structure, wherein thesecond gate structure includes the gate insulating layer and a secondgate electrode formed on the gate insulating layer, wherein the secondgate electrode is formed having a second enclosed pattern on the surfaceof the well region, and the second enclosed pattern is surrounded by thefirst region, wherein an area inside the second enclosed pattern isdefined as a third region, and the third region has the secondconductivity type.
 5. The semiconductor device according to claim 4,further comprising: a second isolation region disposed in the thirdregion, wherein the second isolation region is spaced apart from aboundary of the third region.
 16. The semiconductor device according toclaim 15, wherein a ratio of a perimeter length of the second isolationregion to a perimeter length of the third region ranges from about 0.25to about 0.75.
 7. The semiconductor device according to claim 1,wherein: the well region is a P-type well region; the first regionhaving the first conductivity type is an N⁺ conductive region; and thesecond region having the second conductivity type is a P⁺ conductiveregion.
 8. The semiconductor device according to claim 1, wherein thefirst gate electrode is a polysilicon gate, and a distance betweenadjacent first gate electrodes ranges from about 0.1 μm to about 2 μm.9. The semiconductor device according to claim 2, wherein an innercontour and an outer contour of the first enclosed pattern, and an outercontour of the first isolation region, have at least one of thefollowing shapes: quadrilateral, pentagonal, hexagonal, octagonal,circular, and elliptical.
 10. The semiconductor device according toclaim 4, wherein an outer contour and an inner contour of the firstenclosed pattern, and an outer contour and an inner contour of thesecond enclosed pattern, have the same respective shapes.